1. Field of the Invention
The present invention relates to a vision device, particularly to a night vision device. More particularly, the present invention relates to a night vision device of the ANVIS (aviator's night vision imaging system) type, including a pair of monocular night vision scopes which are mounted and associated with one another in such a way as to provide the user of the device with binocular vision, thereby allowing the user to enjoy a night-time view with depth perception.
2. Description of Related Art
A conventional binocular ANVIS night vision device is depicted in U.S. Pat. No. 4,449,787, issued 22 May 1984, to James Burbo, et al, (the '787 patent) in which a pair of monocular night vision scopes are carried upon a mounting assembly. This mounting assembly provides for vertical adjustment of the monocular night vision scopes, as well as their adjustment for tilt, eye relief, and symmetrical interpupillary distance of the user.
A deficiency of the night vision device taught by Burbo in the '787 patent is that the user of the device must symmetrically adjust the monocular night vision scopes to provide a proper interpupillary distance so that the user enjoys binocular vision and depth perception. Unfortunately, the helmet or face plate which carries the night vision device may not naturally set on the user's head centered between the user's eyes. Such may be the case for a variety of reasons including individual variations in the helmets used, as well as non symmetries of the user's head conformation. In this case, the user of the night vision device will not be able to achieve a completely satisfactory adjustment of the monocular scopes to provide binocular vision and depth perception.
In addition, as the helmet or face plate settles during a period of wearing, shifts about slightly with the movements of the user, or with vibrations of the helicopter or other aircraft on which the user is riding, the user will be distracted as the quality of binocular vision and depth perception changes. This variation in view can be very distracting in the stressful environment in which such night vision devices are used. The human factors engineering of devices which are to be used in such high stress environments where the safety of flight operations can be affected not only by the utility of a device but also by how convenient and easy to use, or "user friendly", the device is, can easily be appreciated
Another ANVIS type of device which provides a night time view using both of the user's eyes and which provides for individual adjustment of interpupillary distance is seen in U.S. Pat. No. 4,463,252, issued 31 July 1984, to T. M. Brennan, et al, (the '252 patent). However, a night vision device according to the '252 patent includes only a single image intensifier assembly. The view provided to each of the user's eyes is a respective right or left half of the image provided by this singular image intensifier assembly. Consequently, the device according to the '252 patent cannot provide true binocular vision with depth perception.
Yet another conventional binocular night vision device is known as the ANVIS 6 in which a pair of night vision monoculars are suspended in front of the user's eyes by a frame which is rectangular in plan view. The frame is supported from a face plate or helmet which the user wears in order to support the weight of the night vision device. The conventional ANVIS 6 includes an interpupillary distance adjustment mechanism with a pair of transversely aligned rotatable shafts, each drivingly coupled to the other at adjacent ends thereof, and each extending within the rectangular frame above one of the monocular scopes. Each shaft defines a respective thread portion of opposite hand, and the rectangular flame slidably carries a pair of depending monocular mounts each threadably engaging one of the threaded shafts. One of the threaded shafts includes an outwardly projecting knob rotation of which rotates both shafts and simultaneously moves the monocular mounts symmetrically together or apart to adjust interpupillary distance to the preferences of the user.
The conventional ANVIS 6 also includes a tilting mechanism which includes an elongate eccentric bushing device which is rotatable in the rectangular frame. This rotatable bushing carries the threaded shafts of the interpupillary adjustment mechanism, and moves these shafts in an arcuate path to tilt the monocular mounts relative to the rectangular frame about a slide and pivot shaft which is carried also by this frame.
With the interpupillary adjustment mechanism of the ANVIS 6, the user is also constrained to a symmetrical positioning of the night vision monocular. Also, each of the monocular mounts must be a separate piece, as are the two threaded shafts. This requirement for separate pieces increases the manufacturing costs of the ANVIS 6, while also increasing the logistics burden for repair and maintenance of the device.